Harmonic Vibrational Frequencies Research Articles

Ab initio investigation of the ground and excited states of TcO+ and RhO+

High-level quantum calculations are utilized to analyze nineteen and thirteen lowest energy electronic states of TcO+ and RhO+. Their potential energy curves, equilibrium bond lengths, electronic excitation energies, harmonic vibrational frequencies, and anharmonicities are reported using quadruple-ζ and quintuple-ζ quality correlation consistent basis sets. The core electron correlation effects and equilibrium chemical bonding patterns of several low-energy electronic states are also considered. The ground state of TcO+ (11Ʃ+) (1σ21π41δ4) is triple bonded in nature, results adiabatically from the high energy Tc+(3P) + O(3P) fragments, and relates to the first excited state of TcO (2Σ+) (1σ22σ11π41δ4). The chemical bonding of TcO+(11Ʃ+) is identical to its isoelectronic RuO2+ (X1Ʃ+) ground state. The ground state of RhO+ (3Σ−) features a 1σ21π41δ42π2 electronic configuration. Moving from TcO+ to RhO+ the binding energy decreases by ∼15−20 kcal/mol, the metal-oxygen bond shortens by 0.07 Å, and the harmonic stretching frequency decreases by ∼170 cm−1. Bonding patterns and spectroscopic constants are compared for the neighboring species of RhO+ and TcO+.

Infrared Spectra of Hydrogen-Bonded Molecular Complexes Under Spatial Confinement.

Infrared (IR) spectroscopy is commonly used in chemical laboratories to study the geometrical structure of molecules and molecular complexes. The analysis of experimental IR spectra can nowadays be reliably supported by the results of quantum-chemical computations as vibrational frequencies and corresponding vibrational transition intensities are routinely calculated using harmonic approximation by virtually all quantum chemistry packages. In the present study we combine the methodology of computing vibrational spectra using high-level electron correlation treatments with an analytical potential-based approach to take into account spatial confinement effects. Using this approach, we perform a pioneering analysis of the impact of the spatial confinement caused by a cylindrical harmonic oscillator potential on the harmonic vibrational transition intensities and frequencies of two hydrogen-bonded complexes: HCN…HCN and HCN…HNC. The emphasis is put on the largest-intensity bands, which correspond to the stretching vibrations. The obtained results demonstrate that embedding the molecular complexes in an external confining potential causes significant changes of transition intensities and vibrational frequencies.

Density functional theoretical study, spectroscopic characterization and molecular docking of the diuretic drug, spironolactone, adsorbed on AuNPs surface and in-vitro studies based on anticancer activity studies against A549 lung cancer cell line

In this study, the geometry, intramolecular charge transfer interactions, and harmonic vibrational frequencies of the diuretic drug, Spironolactone (SPL) and SPL adsorbed on gold nanoparticle (SPLA molecule) were investigated with the help of density functional theory method. Both molecules were found to be stabilized by intramolecular hydrogen bonds C7-H37. O27 and C16-H47. O2, as well as intramolecular charge transfer interactions. These interactions were quantitatively confirmed using natural localized molecular orbitals (NLMOs) analysis. The frontier molecular orbital analysis provided a comparative picture of the reactivity, showing a low value of the energy gap, revealing electron transport in the molecule. The most reactive sites of the molecules were predicted by the molecular electrostatic potential map analysis together with the study of local and global reactivity descriptors. FT-IR and Raman spectral analysis confirmed the existence of significant hydrogen bonding, and charge delocalization in the molecules. Molecular docking performed for the biological activity screening of both molecules along with the SERS and MTT assay (in vitro) analysis confirmed their cancer activity. All the comparative results lead to the conclusion that SPLA possess enhanced therapeutic activity than SPL and hence can be used for effective label-free monitoring of cells in-vitro.

Theoretical prediction of FNgM3–kHk (Ng = Ar, Kr, Xe, and Rn; M = Cu, Ag and Au; k = 0–2) molecules

Recent finding on the unprecedented enhancement of noble gas-noble metal bonding strength on hydrogen doping in van der Waals type cationic complexes motivates us to explore the possibility of occurrence of noble gas (Ng) inserted neutral compounds involving prototype noble metal trimeric ions. MP2 and DFT based methods have been employed to investigate the structures, stabilities, energetics, harmonic vibrational frequencies, and charge distribution of the predicted neutral FNgM3, FNgM2H, and FNgMH2 (Ng = Ar, Kr, Xe, Rn; M = Cu, Ag, Au). All the predicted molecules are thermodynamically stable with respect to all plausible 2-body and 3-body dissociation channels, except the global minima products. However, sufficient large barrier heights provide enough kinetic stability to the predicted metastable molecules, which in turn can prevent them to dissociate into their respective global minima products. All the results clearly indicate that Ng–M bond has partial covalent character while an ionic interaction is found between F and Ng atoms in FNgM3−kHk (k = 0−2). Furthermore, the charge distribution and AIM analyses suggest that the predicted metastable FNgM3−kHk molecules should essentially exist in the form of [F]δ−[NgM3−kHk]δ+. All the results emphasise that it might be possible to prepare and characterise these predicted molecules by suitable experimental technique(s). Exploration of noble gas-noble metal bonding strength on neutralisation of prototype NgM3−kHk + (Ng = Ar, Kr, Xe, and Rn; M = Cu, Ag, and Au; k = 0−2) ions by fluoride anions through ab initio quantum chemical calculations.

Investigation of Formic Acid involved Molecular Clusters with Atmospheric Acidic, Basic and Neutral Species

New particle formation (NPF) is regarded as a main source of tropospheric aerosols. Formic acid (FA) is investigated as a source of NPF by studying its dimer, trimer and tetramer clusters with atmospheric nucleating species like H2O, H2S, MeNH2 and H2O2 employing quantum chemical methods. The structural characteristics, nature of interactions, interaction energies, harmonic vibrational frequencies, thermochemistry at ambient and tropospheric conditions are investigated employing DFT and MP2 methods. Acidic (H2S), basic (MeNH2) and neutral (H2O) nucleating precursors are chosen to study the effect of nature of these species on NPF. Results show that clusters of formic acid with MeNH2 have more stabilising effect than clusters with H2O, H2S and H2O2. The FA-MeNH2 clusters are formed spontaneously at ambient conditions while for others (H2O, H2O2) although the clusters are stable at ambient conditions, yet have positive binding free energy that becomes negative at tropospheric conditions. The cluster formation leads to significant red shifts and increased IR intensities for conventional hydrogen bond donor bond stretching vibrations relative to its monomeric units. For all the nucleating species, stability increases with the growth of clusters.

DFT Studies on Molecular Structure, Thermodynamics Parameters, HOMO-LUMO and Spectral Analysis of Pharmaceuticals Compound Quinoline (Benzo[b]Pyridine)

Advances in computational chemistry have greatly increased its effectiveness and attractiveness as an emerging adjunct to experimental chemistry but also as an independent research field. This work studied some basic bonding Parameters, geometry, Uv-Visible spectra, HOMO-LUMO and harmonic vibrational frequencies of Quinoline were investigated by using density functional theory (DFT/6-31+ (d, p)) methods. The calculated wave numbers (B3LYP) agree properly with the determined wave numbers. The results obtained are then as compared with experimental statistics in which available. The structural parameters; thermochemistry, rotational constants, IR spectra and frequencies, bond distances, angles and dipole moment were obtained from the optimized stable geometries of the compound. The computed optimized geometric bond lengths and bond angles show good agreement with experimental data of the title compound. The calculated HOMO and LUMO energies indicate that charge transfer occurs within the molecule.

Density functional theory on ionic liquid as carbonate scale dissolver in petroleum pipelines

The carbonate scale is the common oilfield scale found in the petroleum pipeline, which will cause flow assurance problems. In the purpose to conquer this problem, the alternative approach is to use ionic liquids (ILs) particularly in dissolving carbonate scale. The main objective of this study is to determine the effective ILs to dissolve carbonate scale in petroleum pipelines, and to evaluate the effect of intermolecular interaction in ILs toward their properties such as dissolution capabilities. The density functional theory (DFT) calculation is used to investigate the intermolecular interaction of a series of different ion pair, namely cations and anions-based of ILs with carbonate ion. All the calculations are completed by Gaussian software at the hybrid Becke 3-Lee-Yang-Parr (B3LYP) level using the 6-311++G(d, p) basis set. The optimized structure of carbonate ion and ion pairs of ILs have been obtained from the calculation which was further complemented by harmonic vibrational frequency, binding energies, bond type, bond order, and natural bond orbital (NBO). The binding energy for the cation and anion-based ILs are obtained where the ammonium ion is −302.2627 kJ/mol and tetrafluoroborate ion is −562.9194 kJ/mol which depict to have the highest value compare to others. Both of them are made up of the single bond and are characterized as the polar covalent bond. The NBO analysis pointed out the higher second-order perturbation energy, E (2) for ammonium ion is at a lone pair, LP (1) N 9 to antibonding sigma, BD*(1) O 3H 6 while BF4 ion is at lone pair LP (3) F 2 to antibonding lone pair, LP*(1) Ca 6. The selective ILs, ammonium tetrafluoroborate shown the higher negative binding energy which is −371.93 kJ/mol having the same nature of bond type and bond order from the findings in cation and anion-based ILs.

Molecular Docking and Quantum Chemical Computations of 4-Chloro-2-[(furan-2-ylmethyl)amino]-5-sulfamoylbenzoic Acid Based on Density Functional Theory

Quantum computational calculations of energies and geometries of 4-chloro-2-[(furan-2-ylmethyl)amino]-5-sulfamoylbenzoic acid have been performed by DFT level of theory using B3LYP/6-31G(d,p) basis set. The solid phase FT-Raman and FT-IR spectra of the Furosemide compound were recorded in the region 4000 cm−1 to 400 cm−1 and 4000 cm−1 to 400 cm−1 respectively. The molecular geometry, harmonic vibrational frequencies and bonding features of 4-chloro-2-[(furan-2-ylmethyl)amino]-5-sulfamoylbenzoic acid in the ground state have been calculated by using density functional theory (DFT) B3LYP method with standard 6–31 G(d,p) basis set. The scaled theoretical wavenumber showed very good agreement with the experimental values. The vibrational assignments were performed on the basis of the total energy distribution (TED) of the vibrational modes. Stability associated with molecule as a result of hyperconjugative interactions, charge delocalization has been analyzed utilizing Natural Bond Orbital (NBO) analysis through the use of B3LYP/6-31G(d,p) technique. The outcomes reveal that electron density (ED) within the σ* and π* orbitals which are antibonding second-order delocalization energies E (2) confirm the occurrence of intramolecular charge transfer (ICT) inside the molecule. Hirshfield surface analysis and Fukui functions calculation were also performed. From the calculations the first order hyperpolarisability was found to be 3.136 × 10−30esu. The molecule orbital contributions have been analyzed utilizing the total (TDOS), partial (PDOS), and overlap population (OPDOS) density of states. A molecular docking study has supported the anticonvulsant activity of the Furosemide molecule.

Synthesis, spectral, structural, DFT and NLO studies of cerium(III) and thorium(IV) complexes of 1-(5-(1-(2-aminophenylimino)ethyl)-2,4-dihydroxyphenyl)ethanone

Reactions of cerium(III) and thorium(IV) nitrates with the Schiff base 1-(5-(1-(2-aminophenylimino)ethyl)-2,4-dihydroxyphenyl)ethanone (H2L) gave two neutral mononuclear complexes, [Ce(HL)(NO3)2(H2O)]·EtOH (1) and [Th(HL)(NO3)3(H2O)]·6H2O (2), respectively. The complexes were characterized by elemental and thermal analyses, IR, electronic, 1H NMR and mass spectra, molar conductivity and magnetic susceptibility measurements. Analytical and spectroscopic methods illustrated that the Schiff base acts as a monoanionic tridentate N2O-ligand. This paper shows a correlation between the structure of the cerium(III) and thorium(IV) complexes experimentally and theoretical study on molecular structure, thermo-chemical parameters and the harmonic vibration frequencies of them. The geometrically optimized structures of the complexes are non-planar. HOMO and LUMO gap energy is small, the charge transfer occurring within cerium(III) and thorium(IV) complexes indicates a greater reactivity and conversely, low chemical stability.

Relativistic Four-Component DFT Calculations of Vibrational Frequencies.

We investigate the effect of relativity on harmonic vibrational frequencies. Density functional theory (DFT) calculations using the four-component Dirac–Coulomb Hamiltonian have been performed for 15 hydrides (H2X, X = O, S, Se, Te, Po; XH3, X = N, P, As, Sb, Bi; and XH4, X = C, Si, Ge, Sn, Pb) as well as for HC≡CPbH3. The vibrational frequencies have been calculated using finite differences of the molecular energy with respect to geometrical distortions of the nuclei. The influences of the choice of basis set, exchange–correlation functional, and step length for the numerical differentiation on the calculated harmonic vibrational frequencies have been tested, and the method has been found to be numerically robust. Relativistic effects are noticeable for the heavier congeners H2Te and H2Po, SbH3 and BiH3, and SnH4 and PbH4 and are much more pronounced for the vibrational modes with higher frequencies. Spin–orbit effects constitute a very small fraction of the total relativistic effects, except for H2Te and H2Po. For HC≡CPbH3 we find that only the frequencies of the modes with large contributions from Pb displacements are significantly affected by relativity.

Electronic Structure of RhO2+, Its Ammoniated Complexes (NH3)1-5RhO2+, and Mechanistic Exploration of CH4 Activation by Them.

High-level electronic structure calculations are initially performed to investigate the electronic structure of RhO2+. The construction of potential energy curves for the ground and low-lying excited states allowed the calculation of spectroscopic constants, including harmonic and anharmonic vibrational frequencies, bond lengths, spin-orbit constants, and excitation energies. The equilibrium electronic configurations were used for the interpretation of the chemical bonding. We further monitored how the Rh-O bonding scheme changes with the gradual addition of ammonia ligands. The nature of this bond remains unaffected up to four ammonia ligands but adopts a different electronic configuration in the pseudo-octahedral geometry of (NH3)5RhO2+. This has consequences in the activation mechanism of the C-H bond of methane by these complexes, especially (NH3)4RhO2+. We show that the [2 + 2] mechanism in the (NH3)4RhO2+ case has a very low energy barrier comparable to that of a radical mechanism. We also demonstrate that methane can coordinate to the metal in a similar fashion to ammonia and that knowledge of the electronic structure of the pure ammonia complexes provides qualitative insights into the optimal reaction mechanism.

Molecular Docking, Topological Analysis and Vibrational Studies on N-(2-Bromoethyl) Succinimide: Antidepressant Agent

N-(2-Bromoethyl) succinimide (N2BES) is a compound with antidepressant pharmacological properties. N-(2-Bromoethyl) succinimide was analyzed for its structural, electronical, vibrational, topological, and biological properties. The molecular geometrical parameters such as bond lengths (Å), bond angles (º), and dihedral angles (º) of N2BES and harmonic vibrational frequencies were investigated using the density functional theory calculations with the B3LYP/6-311++G(d,p) level of theory. Experimental vibrational frequencies of N2BES were recorded in the region of 4000–400 cm-1 (FT-IR) and 4000–100 cm-1 (FT-Raman) and compared with the theoretical frequencies on the basis of potential energy distribution (PED) analysis. Frontier molecular orbitals (FMOs), global reactivity descriptors, the density of states (DOS) properties, molecular electrostatic potential (MEP), natural bond orbital (NBO) analysis, topological analysis of the reduced density gradient (RDG), localized orbital locator (LOL), and bond critical points (BCP) for N2BES were investigated by theoretical calculations. The experimental UV-Vis was measured within 200-500 nm and electronic transitions of absorption wavelength (λ), excitation energies (E), oscillator strengths (f), and ethanol solvent were calculated. In addition, the molecular docking study of the title molecule predicted its binding orientation in the active site of the target serotonin 1A (5-HT1A) protein.

Spectroscopic and quantum chemical study on a non-linear optical material 4-[(1E)-3-(5-chlorothiophen-2-yl)-3-oxoprop-1-en-1-yl] phenyl4-methylbenzene-1-sulfonate

Chalcone derivatives are known for their characteristic non-linear optical efficiency. In the present work, the relation between the molecular structure and non-linear optical properties of a synthesized chalcone derivative 4-[(1E)-3-(5-chlorothiophen-2-yl)-3-oxoprop-1-en-1-yl] phenyl4-methylbenzene-1-sulfonate (4TPMS) have been investigated by combined experimental and theoretical approaches. The title compound 4TPMS was characterized by spectroscopic techniques viz. Raman, FT-IR, UV-vis, and 1H NMR. Further, the experimental findings were validated by quantum chemical computations. The crystalline geometry of 4TPMS was optimized to energy minima by employing density functional theory (DFT) with B3LYP/6-311++G(d,p) approximation level. Harmonic vibrational frequencies were calculated and the spectral assignments have been done by potential energy distribution (PED) analysis. Significant non-linear optical (NLO) responses of chalcone are mainly caused by charge delocalization between lone pair and antibonding molecular orbitals within the molecule. Hence, natural bond orbital (NBO) was performed to analyze the charge delocalization along with the stability of the molecule. The population analysis based on Charges from Electrostatic Potentials using a Grid based method (CHELPG) was employed to understand the electrophilic/nucleophilic reaction sites.Moreover, the time-dependent density functional theory (TD-DFT) was employed to predict the energies, absorption wavelengths (λmax) and oscillator strengths (f) of the electronic transitions. The TD-DFT calculation successfully reproduces the experimental UV-Vis spectrum of 4TPMS. The chemical shifts observed in 1H-NMR and the calculated GIAO shielding tensors also showed good agreement. A vibrational contribution to the NLO activity and the effect of charge delocalization on the NLO response were illustrated by comparing the similar kind of chalcone derivatives.

Fock-space relativistic coupled cluster study on the spectroscopic properties of the low-lying states of the radium monobromide RaBr molecule

The potential energy curves of the ground and five low-lying excited states of the RaBr molecule are calculated using the Fock-space relativistic coupled cluster theory for the first time. A number of properties such as the electronic term energies, equilibrium internuclear distances, transition and permanent dipole moments, sequences of vibrational energies, harmonic vibrational frequencies, Franck–Condon factors, and radiative lifetimes are predicted. The results of this study show that RaBr molecules can be used for the direct laser cooling. The comparison to the previous theoretical studies of the RaF and RaCl molecules is also provided.

Relative energetics of CH3CH2O, CH3CHOH, and CH2CH2OH radical products from ethanol dehydrogenation.

This study has examined the relative energetics of nine stationary points associated with the three different radical isomers generated by removing a H atom from ethanol at the O atom (ethoxy, CH3CH2O), the α C atom (CH3CHOH), and the β C atom (CH2CH2OH). For the first time, CCSD(T) geometry optimizations and harmonic vibrational frequency computations with the cc-pVTZ and aug-cc-pVTZ basis sets have been carried out to characterize two unique minima for each isomer along with three transition state structures with Cs symmetry. Explicitly correlated CCSD(T) computations were also performed to estimate the relative energetics of these nine stationary points near the complete basis set limit. These benchmark results were used to assess the performance of various density functional theory (DFT) and wave function theory methods, and they will help guide method selection for future studies of alcohols and their radicals. The structures generated by abstracting H from the α C atom have significantly lower electronic energies (by at least 7kcal mol-1) than the CH3CH2O and CH2CH2OH radicals. Although previously reported as a minimum on the ground-state surface, the 2A″ Cs structure of the ethoxy radical was found to be a transition state in this study with MP2, CCSD(T), and a number of DFT methods. An implicit solvation model used in conjunction with DFT and MP2 methods did not qualitatively change the relative energies of the isomers, but the results suggest that the local minima for the CH3CHOH and CH2CH2OH radicals could become more energetically competitive in condensed phase environments, such as liquid water and ethanol.

Pseudospectral implementations of long-range corrected density functional theory.

We have implemented pseudospectral density-functional theory (DFT) with long-range corrected DFT functionals (PS-LRC) in quantum mechanics package Jaguar, and applied it in the calculations of geometry optimizations, dimmer interaction energies, polarizabilities and first-order hyperpolarizabilities, harmonic vibrational frequencies, S1 and T1 excitation energies, singlet-triplet gaps, charge transfer numbers, oscillator strengths, reaction barrier heights, electron-transfer couplings, and charge-transfer excitation energies. From our accuracy benchmark analysis, PS grids, PS dealiasing functions, PS atomic corrections, PS multigrid strategy, PS length scales, and PS cutoff scheme perform well in PS DFT with LRC density functionals with very small and ignorable deviations when compared to the conventional spectral (CS) method. The timing benchmark study of S1 excitation energy calculations of fullerenes (Cn , n up to 540) demonstrates that PS-LRC achieves 1.4-8.4-fold speedups in SCF, 22-32-fold speedups in Tamm-Dancoff approximation, and 6-15-fold speedups in total wall clock time with an average error 0.004 eV of excitation energies compared to the CS method.

Fock-space relativistic coupled cluster study on the RaF molecule promising for the laser cooling

The potential energy curves of the ground and five low-lying excited terms of the RaF molecule are calculated using the Fock-space relativistic coupled theory. The electronic term energies, equilibrium internuclear distances, transition and permanent dipole moments, sequences of vibrational energies, harmonic vibrational frequencies, Franck–Condon factors, and radiative lifetimes are predicted. The calculated spectroscopic constants are in good agreement with the available theoretical and experimental data. The scheme for the direct laser cooling involving the first excited A2П1/2 state is proposed. The data obtained in this study suggests the A2П1/2 → X2Σ+ channel in the RaF molecule is the almost ideal case for direct laser cooling. It is quite possible that the effective cooling scheme for the RaF molecule can be realized using only one pump laser.

Tracking the Amide I and αCOO- Terminal ν(C=O) Raman Bands in a Family of l-Glutamic Acid-Containing Peptide Fragments: A Raman and DFT Study.

The E-hook of β-tubulin plays instrumental roles in cytoskeletal regulation and function. The last six C-terminal residues of the βII isotype, a peptide of amino acid sequence EGEDEA, extend from the microtubule surface and have eluded characterization with classic X-ray crystallographic techniques. The band position of the characteristic amide I vibration of small peptide fragments is heavily dependent on the length of the peptide chain, the extent of intramolecular hydrogen bonding, and the overall polarity of the fragment. The dependence of the E residue’s amide I ν(C=O) and the αCOO− terminal ν(C=O) bands on the neighboring side chain, the length of the peptide fragment, and the extent of intramolecular hydrogen bonding in the structure are investigated here via the EGEDEA peptide. The hexapeptide is broken down into fragments increasing in size from dipeptides to hexapeptides, including EG, ED, EA, EGE, EDE, DEA, EGED, EDEA, EGEDE, GEDEA, and, finally, EGEDEA, which are investigated with experimental Raman spectroscopy and density functional theory (DFT) computations to model the zwitterionic crystalline solids (in vacuo). The molecular geometries and Boltzmann sum of the simulated Raman spectra for a set of energetic minima corresponding to each peptide fragment are computed with full geometry optimizations and corresponding harmonic vibrational frequency computations at the B3LYP/6-311++G(2df,2pd) level of theory. In absence of the crystal structure, geometry sampling is performed to approximate solid phase behavior. Natural bond order (NBO) analyses are performed on each energetic minimum to quantify the magnitude of the intramolecular hydrogen bonds. The extent of the intramolecular charge transfer is dependent on the overall polarity of the fragment considered, with larger and more polar fragments exhibiting the greatest extent of intramolecular charge transfer. A steady blue shift arises when considering the amide I band position moving linearly from ED to EDE to EDEA to GEDEA and, finally, to EGEDEA. However, little variation is observed in the αCOO− ν(C=O) band position in this family of fragments.

Identification of the photoelectron spectra of HFCS via computing Franck–Condon factors

Some peaks present in the photoelectron spectrum of a mixture were proposed to be produced from thioformyl fluoride (HFCS) by Baker et al. (J. Phys. Chem. 99 (1995) 10147). This study aimed to identify whether the observed peaks were arisen from HFCS. We calculated the equilibrium structures and harmonic vibrational frequencies of HFCS and some ionic states of HFCS+ using the B3LYP, PBE0, M06-2X, and CCSD(T) approaches. We also simulated the photoelectron spectra of HFCS via computing Franck–Condon factors. The adiabatic ionization energies were computed using the CCSD(T) method combined with the complete basis set limit approach. A new ionic state of HFCS+ possessing a nonplanar structure was discovered. Both the simulated photoelectron spectrum and calculated adiabatic ionization energies of HFCS are in agreement with the experiments. Accordingly, we confirm that the reactive molecule HFCS can be identified using the photoelectron spectroscopic techniques.

Spectroscopic Study of the B 1Π State of NaH.

In this study, the B1Π excited state of NaH has been experimentally studied for the first time. Pulsed laser-induced fluorescence excitation spectroscopy was used to investigate the B1Π electronic state of NaH. A total of 48 ro-vibronic transitions were observed, including within the B–X (0–0) and B–X (0–1) transition bands. Only one B-state vibrational level was identified, and a series of PQR lines, with eight e-parity and eight f-parity sublevels (v′ = 0, J′ = 1–8), were assigned. The level assignment was supported by a comparison of the experimental line positions with the ab initio calculations, the dispersed laser-induced fluorescence spectrum of the NaH B1Π → X1∑+ emission, and the V-type optical–optical double resonance spectra. The Dunham-type coefficients, the mean internuclear distance, the harmonic vibrational frequency ω, and the dissociation energies D0 and De of the B1Π state were determined.